The invention relates to a self-locking belt retractor with a locking device that is activated in a vehicle-sensitive and/or belt-sensitive manner, whereby the belt retractor has as a force-limiting device a torsion bar that allows, when the locking member is engaged a limited belt removal and is connected, on the one hand, to the belt reeling shaft and, on the other hand, by a profiled head to the locking member of the belt retractor. A device for adjusting the energy absorption of the torsion bar and adjusting the torsion bar to preselected incidents of loading is switched in the force-transmitting path between the torsion bar and the belt reeling shaft.
A self-locking belt retractor with the aforementioned features is known from DE 27 27470 A1. Inasmuch as the known belt retractor has a torsion bar as a force-limiting device, for an individual adjustment of the force level of the belt force limitation to the respective parameters set by the passenger, a continuos change of the clamping length of the torsion bar as a function of the weight of the passenger seated in the vehicle seat and/or of the allowed forward movement path is realized. For this purpose, a sliding sleeve connected to the belt reeling shaft and adjustable over the length of the torsion bar is provided which can be moved by an actuating device and, depending on its position, determines the torsion force and thus the free torsion length of the torsion available for force limitation.
In theory, the clamping length does not affect the force level for the belt force limitation, instead only the energy absorption capacity of the torsion bar is changed. Practical experiments in this context have shown that the effect of the clamping length of the torsion bar onto the force level is minimal and is not sufficient for practical applications. The invention has therefore the object to improve a belt retractor of the aforementioned features such that a change of the force level is possible over a wide adjustment range and furthermore also possible directly at the beginning or during an accident as a function of the loading conditions occurring in individual situations.